This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. As many as 35% of all domesticated cats in the U.S. are obese, resulting primarily from an unlimited food supply that requires almost no physical effort to obtain. In cats, there is a strong correlation between BMI and insulin resistance, but little is known about hepatic fluxes in obese versus lean cats. This study was designed to determine hepatic fluxes in lean and obese cats on a high carbohydrate versus high fat diet.